Power semiconductor device

ABSTRACT

A power semiconductor device includes: a semiconductor body; a first load terminal structure coupled to the body front side and a second load terminal structure coupled to the body backside; an active area for conducting a load current between the load terminal structures; a drift region having a first conductivity type; a backside region arranged at the backside and including, inside the active area, first and second backside emitter zones. At least one of the backside emitter zones includes: first sectors each having at least one first region of a second conductivity type, the first region arranged in contact with the second load terminal structure and having a smallest lateral extension of at most 50 μm; and/or second sectors each having a second region of the second conductivity type arranged in contact with the second load terminal structure and having a smallest lateral extension of at least 50 μm.

TECHNICAL FIELD

This specification refers to embodiments of a power semiconductordevice. In particular, this specification refers to aspects of a powersemiconductor device having one or more backside emitter zones includedin a semiconductor body, wherein the backside emitter zones exhibitdifferent emitter efficiencies and/or different injection efficiencies.

BACKGROUND

Many functions of modern devices in automotive, consumer and industrialapplications, such as converting electrical energy and driving anelectric motor or an electric machine, rely on power semiconductordevices. For example, Insulated Gate Bipolar Transistors (IGBTs), MetalOxide Semiconductor Field Effect Transistors (MOSFETs) and diodes, toname a few, have been used for various applications including, but notlimited to switches in power supplies and power converters.

A power semiconductor device usually comprises a semiconductor body withan active area configured to conduct a load current along a load currentpath between two load terminals of the device. During operation of sucha power semiconductor device, a spatial temperature distribution in thesemiconductor body generally tends to be inhomogeneous, exhibiting,e.g., a maximum at the center of the active area. As a consequence, apower cycling reliability and a thermal short circuit or surge currentwithstand capability of the power semiconductor device may be reduced,which may necessitate the provision of costly safety margins in thethermal design of the power semiconductor device.

It is thus desirable to influence, for example homogenize, thetemperature distribution in the semiconductor body of a powersemiconductor device, so as to increase the device reliability. Further,it may be desirable to improve a tradeoff between softness and powerlosses of a power semiconductor device.

SUMMARY

Aspects described herein relate to a specific novel design of a backsideregion of a power semiconductor device that may, for example, yield animproved thermal robustness and an improved tradeoff between softnessand power losses as compared to conventional designs.

According to an embodiment, a power semiconductor device comprises: asemiconductor body having a front side and a backside; a first loadterminal structure being coupled to the front side and a second loadterminal structure being coupled to the backside; an active area of thesemiconductor body being configured for conducting a load currentbetween the first load terminal structure and the second load terminalstructure; a drift region of the semiconductor body, the drift regionhaving a first conductivity type and being configured for conducting theload current; a backside region of the semiconductor body, the backsideregion being arranged at the backside and comprising, inside the activearea, a first backside emitter zone and a second backside emitter zone.At least one of the first backside emitter zone and the second backsideemitter zone comprises: a plurality of first sectors each comprising atleast one first region of a second conductivity type, the first regionbeing arranged in contact with the second load terminal structure andhaving a smallest lateral extension of at most 50 μm; and/or a pluralityof second sectors each consisting of a second region of the secondconductivity type, the second regions being arranged in contact with thesecond load terminal structure and having a smallest lateral extensionof at least 50 μm. The second backside emitter zone differs from thefirst backside emitter zone at least in one of the following: thepresence of first sectors; the presence of second sectors; a smallestlateral extension of first sectors; a smallest lateral extension ofsecond sectors; a lateral distance between neighboring first sectors; alateral distance between neighboring second sectors; a smallest lateralextension of the first regions; a lateral distance between neighboringfirst regions within the same first sector.

According to another embodiment, a power semiconductor device comprises:a semiconductor body having a front side and a backside; a first loadterminal structure being coupled to the front side and a second loadterminal structure being coupled to the backside; an active area of thesemiconductor body being configured for conducting a load currentbetween the first load terminal structure and the second load terminalstructure; a drift region of the semiconductor body, the drift regionhaving a first conductivity type and being configured for conducting theload current; a backside region of the semiconductor body, the backsideregion being arranged at the backside and comprising, inside the activearea, a first backside emitter zone and a second backside emitter zone,wherein at least one of the first backside emitter zone and the secondbackside emitter zone comprises: a plurality of second sectors eachconsisting of a second region of the second conductivity type, thesecond regions being arranged in contact with the second load terminalstructure and having a smallest lateral extension of at least 50 μm;wherein the first backside emitter zone exhibits each of a first emitterefficiency and a first injection efficiency; wherein the second backsideemitter zone exhibits each of a second emitter efficiency and a secondinjection efficiency at a nominal current of the power semiconductordevice; wherein the first emitter efficiency differs from the secondemitter efficiency by at least 1% or even by at least 3% or even by atleast 10% and/or the first injection efficiency differs from the secondinjection efficiency by at least 1% or even by at least 3% or even by atleast 10%.

For example, the above-stated relation between the first injectionefficiency and the and second injection efficiency may refer to thefirst and second injections efficiencies at a current amounting to 0.1times a nominal current of the power semiconductor device.

Alternatively, the above-stated relation between the first injectionefficiency and the second injection efficiency may refer to the firstand second injections efficiencies at a nominal current of the powersemiconductor device or at twice the nominal current of the powersemiconductor device.

According to a further embodiment, a power semiconductor devicecomprises: a semiconductor body having a front side and a backside; afirst load terminal structure being coupled to the front side and asecond load terminal structure being coupled to the backside; an activearea of the semiconductor body being configured for conducting a loadcurrent between the first load terminal structure and the second loadterminal structure; a drift region of the semiconductor body, the driftregion having a first conductivity type and being configured forconducting the load current; a backside region of the semiconductorbody, the backside region being arranged at the backside and comprising,inside the active area, a first backside emitter zone and a secondbackside emitter zone, wherein each of the first backside emitter zoneand the second backside emitter zone comprises a plurality of regions ofa second conductivity type being arranged in contact with the secondload terminal structure and a plurality of regions of the firstconductivity type being arranged in contact with the second loadterminal structure; wherein a dopant concentration in a respectivecentral portion of the regions of the second conductivity type in thefirst backside emitter zone is essentially equal to a dopantconcentration in a respective central portion of the regions of thesecond conductivity type in the second backside emitter zone; wherein adopant concentration in a respective central portion of the regions ofthe first conductivity type in the first backside emitter zone isessentially equal to a dopant concentration in a respective centralportion of the regions of the first conductivity type in the secondbackside emitter zone; wherein the first backside emitter zone exhibitseach of a first emitter efficiency and a first injection efficiency at anominal current of the power semiconductor device; wherein the secondbackside emitter zone exhibits each of a second emitter efficiency and asecond injection efficiency at a nominal current of the powersemiconductor device; wherein the first emitter efficiency differs fromthe second emitter efficiency by at least 1% or even by at least 5% oreven by at least 10% or even by at least 20% and/or the first injectionefficiency differs from the second injection efficiency by at least 1%or even by at least 5% or even by at least 10% or even by at least 20%.

For example, the above-stated relation between the first injectionefficiency and the and second injection efficiency may refer to thefirst and second injections efficiencies at a current amounting to 0.1times a nominal current of the power semiconductor device.

Alternatively, the above-stated relation between the first injectionefficiency and the second injection efficiency may refer to the firstand second injections efficiencies at a nominal current of the powersemiconductor device or at twice the nominal current of the powersemiconductor device.

Those skilled in the art will recognize additional features andadvantages upon reading the following detailed description, and uponviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The parts in the figures are not necessarily to scale. Instead, emphasisis placed upon illustrating principles of the invention. Moreover, inthe figures, like reference numerals designate corresponding parts. Inthe drawings:

FIGS. 1A-B each schematically and exemplarily illustrate a section of avertical cross-section of a power semiconductor device in accordancewith one or more embodiments;

FIGS. 2-12 each schematically and exemplarily illustrate a section of avertical cross-section of a power semiconductor device in accordancewith one or more embodiments;

FIGS. 13A-E each schematically and exemplarily illustrate a section of ahorizontal cross-section of a power semiconductor device in accordancewith one or more embodiments; and

FIGS. 14A-F each schematically and exemplarily illustrate a section of ahorizontal cross-section of a power semiconductor device in accordancewith one or more embodiments.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof and in which are shown byway of illustration specific embodiments in which the invention may bepracticed.

In this regard, directional terminology, such as “top”, “bottom”,“below”, “front”, “behind”, “back”, “leading”, “trailing”, “above” etc.,may be used with reference to the orientation of the figures beingdescribed. Because parts of embodiments can be positioned in a number ofdifferent orientations, the directional terminology is used for purposesof illustration and is in no way limiting. It is to be understood thatother embodiments may be utilized and structural or logical changes maybe made without departing from the scope of the present invention. Thefollowing detailed description, therefore, is not to be taken in alimiting sense, and the scope of the present invention is defined by theappended claims.

Reference will now be made in detail to various embodiments, one or moreexamples of which are illustrated in the figures. Each example isprovided by way of explanation, and is not meant as a limitation of theinvention. For example, features illustrated or described as part of oneembodiment can be used on or in conjunction with other embodiments toyield yet a further embodiment. It is intended that the presentinvention includes such modifications and variations. The examples aredescribed using specific language which should not be construed aslimiting the scope of the appended claims. The drawings are not scaledand are for illustrative purposes only. For clarity, the same elementsor manufacturing steps have been designated by the same references inthe different drawings if not stated otherwise.

The term “horizontal” as used in this specification intends to describean orientation substantially parallel to a horizontal surface of asemiconductor substrate or of a semiconductor structure. This can be forinstance the surface of a semiconductor wafer or a die or a chip. Forexample, both the first lateral (or horizontal) direction X and thesecond lateral (or horizontal) direction Y mentioned below and/or shownin the figures can be horizontal directions, wherein the first lateraldirection X and the second lateral direction Y may be perpendicular toeach other.

The term “vertical” as used in this specification intends to describe anorientation which is substantially arranged perpendicular to thehorizontal surface, i.e., parallel to the normal direction of thesurface of the semiconductor wafer/chip/die. For example, the verticaldirection Z mentioned below and/or shown in the Figures may be adirection that is perpendicular to both the first lateral direction Xand the second lateral direction Y.

In this specification, n-doped is generally referred to as “firstconductivity type” while p-doped is referred to as “second conductivitytype”. Alternatively, opposite doping relations can be employed so thatthe first conductivity type can be p-doped and the second conductivitytype can be n-doped.

In the context of the present specification, the terms “in ohmiccontact”, “in electric contact”, “in ohmic connection”, and“electrically connected” intend to describe that there is a low ohmicelectric connection or low ohmic current path between two regions,sections, zones, portions or parts of a semiconductor device or betweendifferent terminals of one or more devices or between a terminal or ametallization or an electrode and a portion or part of a semiconductordevice. Further, in the context of the present specification, the term“in contact” intends to describe that there is a direct physicalconnection between two elements of the respective semiconductor device;e.g., a transition between two elements being in contact with each othermay not include a further intermediate element or the like.

In addition, in the context of the present specification, the term“electric insulation” is used, if not stated otherwise, in the contextof its general valid understanding and thus intends to describe that twoor more components are positioned separately from each other and thatthere is no ohmic connection connecting those components. However,components being electrically insulated from each other may neverthelessbe coupled to each other, for example mechanically coupled and/orcapacitively coupled and/or inductively coupled. To give an example, twoelectrodes of a capacitor may be electrically insulated from each otherand, at the same time, mechanically and capacitively coupled to eachother, e.g., by means of an insulation, e.g., a dielectric.

Specific embodiments described in this specification pertain to, withoutbeing limited thereto, a power semiconductor device exhibiting a singlecell, a stripe cell or cellular (also referred to as “needle” or“columnar”) cell configuration, e.g., a power semiconductor device thatmay be used within a power converter or a power supply. Thus, in anembodiment, such device can be configured to carry a load current thatis to be fed to a load and/or, respectively, that is provided by a powersource. For example, the power semiconductor device may comprise one ormore active power semiconductor cells, such as a monolithicallyintegrated diode cell, a derivative of a monolithically integrated diodecell (e.g., a monolithically integrated cell of two anti-seriallyconnected diodes), a monolithically integrated transistor cell, e.g., amonolithically integrated IGBT or MOSFET cell and/or derivativesthereof. Such diode/transistor cells may be integrated in a powersemiconductor module. A plurality of such power cells may constitute acell field that is arranged with an active area of the powersemiconductor device.

The term “power semiconductor device” as used in this specificationintends to describe a semiconductor device on a single chip with highvoltage blocking and/or high current-carrying capabilities. In otherwords, such power semiconductor device is intended for high current,typically in the Ampere range, e.g., up to several ten or hundredAmpere, and/or high voltages, typically above 15 V, more typically 100 Vand above, e.g., up to at least 400 V or even more, e.g., in the rangefrom 1.2 kV to 2 kV, or up to at least 3 kV, or even up to 6 kV or more.

For example, the power semiconductor device described below may be asingle semiconductor chip exhibiting a single cell configuration (suchas a single diode cell), a stripe cell configuration or a cellular cellconfiguration and can be configured to be employed as a power componentin a low-, medium- and/or high voltage application.

For example, the term “power semiconductor device” as used in thisspecification is not directed to logic semiconductor devices that areused for, e.g., storing data, computing data and/or other types ofsemiconductor based data processing.

FIG. 1A schematically and exemplarily shows a section of a verticalcross-section of a power semiconductor device 1 in accordance with oneor more embodiments. The power semiconductor device 1 comprises asemiconductor body 10 having a front side 10-1 and a backside 10-2. Forexample, the semiconductor body 10 may comprise or consist of asilicon-based substrate, a silicon carbide-based substrate, a galliumnitride-based substrate or, e.g., another wide band gap semiconductorsubstrate.

The semiconductor body 10 comprises, an active area 15, which may alsobe referred to as an active cell area 15. The active cell area 15 maycomprise one or more power cells 14, which may be configured forconducting and/or a controlling a load current between a first loadterminal structure 11 arranged at the front side 10-1 of thesemiconductor body 10 and a second load terminal structure 12 arrangedat the backside of the semiconductor body 10. Accordingly, in accordancewith some embodiments, the power semiconductor device 1 may beconfigured as a vertical power semiconductor device 1.

For example, the power semiconductor device 1 is or comprises at leastone of: a power diode, a MOSFET, an IGBT, a reverse conducting IGBT(RC-IGBT), a high-electron-mobility transistor (HEMT), such as a galliumbased HEMT, and a thyristor.

In case the power semiconductor device 1 is or comprises a power diode,the active area 15 may comprise, for example, one large power cell 14,as exemplarily illustrated in FIG. 1A. For example, the power cell 14may include a p-doped semiconductor region that is configured as ananode region and that is in contact with a front side metallizationforming part of a first load terminal structure 11. For example, theanode region may form a pn-junction with an n-doped drift region 100 ofthe semiconductor body 10.

Alternatively, in the case of a transistor configuration, e.g., in theform of a MOSFET or an IGBT, the active area 15 may include an activecell field 14 comprising a plurality of transistor cells, which may, forexample, comprise in each case a source region, a body region, and agate electrode (such as a trench gate electrode), the gate electrodeconfigured for selectively switching the power semiconductor device 1 inone of a forward conducting state and a forward blocking state. Thedesign of such active cell fields of power semiconductor devices is, assuch, well known to the person skilled in the art and will therefore notbe explained in further detail here.

Besides the active area 15, the power semiconductor device 1 maycomprise an edge termination region 16 that extends between the activearea 15 and a lateral chip edge (not illustrated) of the semiconductorbody 10. For example, the edge termination region 16 may laterallysurround the active area 15.

As used herein, the terms “edge termination region” and “active area”are both associated with the respective technical meaning the skilledperson typically associates therewith in the context of powersemiconductor devices. That is, the active area 15 is primarilyconfigured for load current conduction and, in the case of a transistorconfiguration, switching purposes, whereas the edge termination region16 primarily fulfills functions regarding reliable blockingcapabilities, appropriate guidance of the electric field, and sometimesalso charge carrier drainage functions, and/or further functionsregarding protection and proper termination of the active area 15.

The edge termination region 16 may comprise an edge terminationstructure 18, which may be arranged at the front side 10-1 of thesemiconductor body 10. Such an edge termination structure 18 may also bereferred to as a junction termination structure or briefly as a junctiontermination. For example, the edge termination structure 18 may compriseone or more components arranged within the semiconductor body 10 and/orone or more components arranged above the front side surface 10-1 of thesemiconductor body 10. In FIG. 1A, the edge termination structure 18 ismerely schematically illustrated as a structure being arranged at thefront side 10-1 inside the semiconductor body 10, without showingspecific structural details.

Common examples of edge termination structures 18 are field rings(sometimes also referred to as guard rings), field plates, a combinationof field rings and field plates, and a junction termination extension(JTE) edge termination structure, such as a variation-of-lateral-doping(VLD) edge termination structure. The skilled person is well acquaintedwith these kinds of edge termination structures as such. Therefore, theywill not be explained in detail at this point.

The power semiconductor device 1 further comprises a backside region 17being arranged inside the semiconductor body 10 at the backside 10-1.The backside region 17 comprises at least one first backside emitterzone 171 and at least one second backside emitter zone 172, wherein thefirst and second backside emitter zones 171, 172 are arranged inside theactive area 15 of the power semiconductor device 1.

FIG. 1A exemplarily shows one first backside emitter zone 171 and onesecond backside emitter zone 172. However, it should be noted that inaccordance with some embodiments, a plurality of first backside emitterzones 171 and/or a plurality of second backside emitter zones 172 may beprovided.

FIG. 1B schematically and exemplarily illustrates a variant embodiment,which differs from the one of FIG. 1A in that the semiconductor body 10additionally comprises a field stop region 100-1. The field stop region100-1 is arranged between the drift region 100 and the backside region17 and has a higher dopant concentration of the first conductivity typethan the drift region 100.

The field stop region 100-1 may exhibit one or more dopant concentrationpeaks. For example, the field stop region 100-1 may have come into beingby means of one or more proton implantations through the back side 10-2.Such methods and variants of field stop regions, which are sometimesalso referred to as buffer regions, are in principle well known to theperson skilled in the art and will therefore not be discussed in furtherdetail here.

In an embodiment, the field stop region 100-1 has been produced by meansof one or more proton implantations, such that an end of range of ashallowest dopant concentration peak is located in at a depth a rangefrom 1 μm to 4 μm below a backside surface of the semiconductor body 10.In this context, the “shallowest” peak shall designate either the onlyfield stop peak (in case there is only one) or the field stop peak outof several field stop peaks that is located closest to the backsidesurface.

In an embodiment, the field stop region 100-1 has been realized by anion implantation of donor-like atoms such as phosphorus, selenium orsulphur with a subsequent drive-in step or annealing step resulting forexample in a Gaussian-like doping profile of the field stop region100-1. In particular the implementation of a field stop region 100-1with deep donors such as selenium atoms the temperature dependence ofthe hole injection by the p-short regions 1711, 1712, 1721, 1722 duringthe turn-off process can be reduced. For a fine-tuning of thistemperature dependence additionally shallow donors can be introducedinto the field stop region 100-1.

In accordance with an embodiment, a respective area extension of each ofthe first backside emitter zone 171 and the second backside emitter zone172 may amount to at least 5%, such as at least 25% or even at least40%, of an area extension of the active area 15.

The first and second backside emitter zones 171, 172 may differ from oneanother with regard to their backside emitter properties.

For example, the at least one first backside emitter zone 171 mayexhibit each of a first emitter efficiency and a first injectionefficiency at a nominal current of the power semiconductor device 1,whereas the at least one second backside emitter zone 171 may exhibiteach of a second emitter efficiency and a second injection efficiency atthe nominal current.

For the purposes of the present specification, the emitter efficiency isdefined as the ratio of the electron current at a backside p/n or n−/n+junction (i.e., at an interface between the field stop region 100-1 andthe first backside emitter zone 171 and/or the second backside emitterregion zone) and the total current, wherein this quantity is averagedover the respective first or second backside emitter zone 171, 172.

Further, for the purposes of the present specification, the injectionefficiency is defined as. the ratio of the amount of injected holesduring the reverse commutation of the power semiconductor device 1 andthe total reverse recovery charge under softness critical conditions(i.e. at a relatively low current, e.g. 0.1 times a nominal current, andat a relatively low temperature, e.g. 25° C.). In other words, theinjection efficiency is the time integral over the hole current into thedevice 1 during reverse recovery compared to the time integral over thetotal current during reverse recovery, typically called Qrr, under saidsoftness critical conditions.

Further, for the purposes of the present specification, an injected holecharge of the first backside emitter zone 171 or of the second backsideemitter zone 172, respectively, is defined as the charge of the injectedholes during the reverse commutation of the power semiconductor device 1under softness critical conditions (i.e. at a relatively low current,e.g. 0.1 times a nominal current, and at a relatively low temperature,e.g. 25° C.). In other words, the injection efficiency is the timelyintegral over the hole current into the device 1 during reverse undersaid softness critical conditions.

Further, for the purposes of the present specification, an averagebackside plasma concentration associated with the first backside emitterzone 171 or the second backside emitter zone 172, respectively, isdefined as an area integral of a free electron concentration over ahorizontal cross-sectional area at a distance of 1 μm from an interfacebetween the field stop region 100-1 and the respective first or secondbackside emitter zone 171, 172, normalized by the area.

In accordance with one or more embodiments, the first emitter efficiencydiffers from the second emitter efficiency by at least 1%, such as by atleast 5%, e.g. by at least 10% or even by at least 20%. Additionally oralternatively, it may be provided that the first injection efficiencydiffers from the second injection efficiency by at least 5%, e.g. by atleast 10% or even by at least 20%.

Further, in accordance with an embodiment, the injected hole charge ofthe first backside emitter zone 171 differs from the injected holecharge of the second backside emitter zone 172 by at least 10%, such as,e.g., by at least 20%, or even by at least 40%.

Further, in accordance with an embodiment, the average backside plasmaconcentration associated with the first backside emitter zone (171)differs from the average backside plasma concentration associated withthe second backside emitter zone (172) by at least 5%, such as by atleast 10%, e.g., by at least 20%.

In terms of structural features, such differences between the first andsecond emitter and/or injection efficiencies and between the respectiveinjected hole charges or average backside plasma concentrations may beachieved, for example, by providing inside the first and/or secondbackside emitter zones 171, 172 a plurality of semiconductor regions ofa second conductivity type (e.g., p-type) that is complementary to afirst conductivity type (e.g. n-type) of the drift region 100.

In other words, as will be explained in more detail below with referenceto FIGS. 2-11, the first backside emitter zone 171 and the secondbackside emitter zone 172 may be configured as meta-structures, eachcomprising different arrangements of regions of the second conductivitytype 1711, 1721, 1712, 1722 being arranged in contact with the secondload terminal structure 12 and a plurality of regions of the firstconductivity type 1740 being arranged in contact with the second loadterminal structure 12. In some embodiments such a meta-structure 171,172 may also be characterized by the absence of regions of the secondconductivity type 1711, 1721, 1712, 1722.

FIGS. 2-11 each schematically and exemplarily illustrate a section of avertical cross-section of a power semiconductor device 1, e.g. a powerdiode, in accordance with one or more embodiments. The cross-sectioncomprises in each case a portion of the semiconductor body 10 at thebackside 10-1, which includes a portion of the field stop region 100-1and a portion of the backside region 17. The illustrated portion of thebackside region 17 comprises a first backside emitter zone 171 as wellas a second backside emitter zone 172. Further, a portion of the secondload terminal structure 12 (in the form of a backside metallization) isshown.

The embodiments of FIGS. 2-11 differ from one another in the specificarrangements of regions of the second conductivity type 1711, 1721,1712, 1722 and of regions of the first conductivity type 1740 inside thefirst and second backside emitter zones 171, 172, as will be explainedin more detail in the following.

In accordance with the embodiments of each of FIGS. 2-11, at least oneof the first backside emitter zone 171 and the second backside emitterzone 172 may comprise a plurality of first sectors 171-1, 172-1 and/or aplurality of second sectors 171-2, 172-2.

The first sectors 171-1, 172-1 as well as the second sectors 171-2,172-2 may be configured such that they do not support any significantinjection of charge carriers of the first conductivity type (e.g.electrons) during operation of the power semiconductor device 1.

For example, each first sector 171-1, 171-2 may comprise at least onefirst region 1711, 1721 of the second conductivity type, the firstregion 1711, 1721 being arranged in contact with the second loadterminal structure 12 and having a smallest lateral extension x1, x1′ ofat most 50 μm, such as at most 30 μm, for example at most 10 μm.

The first regions 1711, 1721 may be configured such that they do notsupport any significant injection of charge carriers of the secondconductivity type (e.g. holes) during operation of the powersemiconductor device 1.

Further, each second sector 171-2, 172-2 may consist of a second region1712, 1722 of the second conductivity type, the second regions 1712,1722 being arranged in contact with the second load terminal structure12 and having a smallest lateral extension x2, x2′ of at least 50 μm,such as at least 100 μm, for example at least 200 μm. In case the secondconductivity type is “p”, the second regions of the second conductivitytype 1712, 1722 may also be referred to as “p-short regions”.

The smallest lateral extension x2, x2′ of these p-short 1712, 1722regions defines the reverse-current-induced lateral voltage drop belowthese regions 1712, 1722 during the turn-off process and with it theonset level of the injection of holes during the turn-off phase.Preferably, the vertical doping profile of these p-short regions 1712,1722 in the center of these regions 1712, 1722 is approximately the samefor all of these regions 1712, 1722. Alternatively, these p-regions1712, 1722 can exhibit different vertical doping profiles.

In contrast to the first regions, 1711, 1721, the second regions 1712,1722 may be configured such that they support injection of chargecarriers of the second conductivity type (e.g. holes) during operationof the power semiconductor device 1.

Laterally in between the sectors 171-1, 172-1, 171-2, 172-2 there areregions of the first conductivity type 1740, which are also arranged incontact with the second load terminal structure 12. A lateral extensionof these regions of the first conductivity type 1740 may be sufficientlylarge such that the regions of the first conductivity type 1740 maysupport injection of charge carriers of the first conductivity type(e.g. electrons) during operation of the power semiconductor device 1.For example, in some embodiments, a lateral extension of the regions ofthe first conductivity type 1740 may amount to at least 50 μm, such asat least 100 μm, for example at least 200 μm.

Correspondingly, in some embodiments, a lateral distance d1, d1′, d2,d2′ between neighboring first and/or second sectors 171-1, 172-1, 171-2,172-2 may amounts to at least 50 μm, such as at least 100 μm, or even atleast 200 μm.

In some embodiments, said regions of the first conductivity type 1740may have a higher dopant concentration of the first conductivity typethan the field stop region 100-1.

For example, the regions of the first conductivity type 1740 may have ahigher dopant concentration of the first conductivity type than anaverage dopant concentration of the first conductivity type in the fieldstop region 100-1, wherein the average is taken over a verticalthickness of the field stop region 100-1. In some embodiments, thevertical thickness of the field stop region 100-1 may be larger than 2μm, such as larger than 5 μm, or even larger than 10 μm.

For example, such relatively high dopant concentrations of the regionsof the first conductivity type 1740 may have come into being by means ofa laser thermal annealing (LTA) process carried out at the backside10-1.

Additionally or alternatively, a dopant concentration of the secondconductivity type of the first regions 1711, 1721 and/or a dopantconcentration of the second conductivity type of the second regions1712, 1722 may also be higher than the dopant concentration of the firstconductivity type of the field stop region 100-1.

For example, first and/or second regions 1711, 1721, 1712, 1722 may havea higher dopant concentration of the second conductivity type than anaverage dopant concentration of the first conductivity type in the fieldstop region 100-1, wherein the average is taken over a verticalthickness of the field stop region 100-1. In some embodiments, thevertical thickness of the field stop region 100-1 may be larger than 2μm, such as larger than 5 μm, or even larger than 10 μm.

In accordance with some embodiments, a dopant concentration in arespective central portion of the regions of the second conductivitytype 1711, 1712 in the first backside emitter zone 171 is essentiallyequal to a dopant concentration in a respective central portion of theregions of the second conductivity type 1721, 1722 in the secondbackside emitter zone 172; and a dopant concentration in a respectivecentral portion of the regions of the first conductivity type 1740 inthe first backside emitter zone 171 is essentially equal to a dopantconcentration in a respective central portion of the regions of thefirst conductivity type 1740 in the second backside emitter zone 172. Inthis context, a statement that dopant concentrations are “essentiallyequal” shall be understood to the effect that one dopant concentrationdiffers from the other dopant concentration at most by a factor of 1.3,such as at most by a factor of 1.1, e.g., at most by a factor of 1.05.

Further, in accordance with some embodiments, it may be provided thatthe second backside emitter zone 172 differs from the first backsideemitter zone 171 at least in one of the following:

-   -   the presence (or absence) of first sectors 171-1, 172-1;    -   the presence (or absence) of second sectors 171-2, 172-2;    -   a smallest lateral extension x11, x11′ of first sectors 171-1,        172-1;    -   a smallest lateral extension x2, x2′ of second sectors 171-2,        172-2;    -   a lateral distance d1, d1′ between neighboring first sectors        171-1, 172-1;    -   a lateral distance d2, d2′ between neighboring second sectors        171-2, 172-2;    -   a smallest lateral extension x1, x1′ of the first regions 1711,        1721;    -   a lateral distance d11, d11′ between neighboring first regions        1711, 1721 within the same first sector 171-1, 172-1.

For example, in the embodiment shown schematically in FIG. 2, the secondbackside emitter zone 172 differs from the first backside emitter zone171 in that first or second sectors 172-1, 172-2 are entirely absent inthe second backside emitter zone 172, whereas the first backside emitterzone 171 comprises a plurality of second sectors 171-2. The secondsectors 171-2 consist of second regions 1712 of the second conductivitytype (e.g., p-short regions), each having lateral extension x2 along thelateral direction of the cross-sections and being arranged at a lateraldistance d2 from one another. A region 1740 of the first conductivitytype having a higher dopant concentration than the field stop region100-1 is in each case arranged in between two neighboring second regions1712 of the second conductivity type.

For example, during operation of the power semiconductor device 1according to the exemplary embodiment of FIG. 2, a relatively low plasmadensity of free charge carriers may result from the presence of thesecond sectors 171-2 in the first backside emitter zone 171. This is tosay that a plasma density in the first backside emitter zone 171 and inportions of the semiconductor body 10 which are located above the firstbackside emitter 171 may be relatively low as compared to a plasmadensity in the second backside emitter zone 172 and in portions of thesemiconductor body 10 which are located above the second backsideemitter region 172.

As a consequence, lower static and dynamic losses may occur in the areaof the first backside emitter zone 171 as compared to the area of thesecond backside emitter zone 172. The first backside emitter zone 171being located closer to a center of the active area 15 than the secondbackside emitter zone 172 (see the portion of the edge terminationregion 173 shown in FIG. 2), the presence of the second sectors 171-2may thus contribute to a temperature homogenization within thesemiconductor body 10.

Further, loss generation may be increased by means of adjusting theemitter efficiency in regions of improved thermal cooling, e.g. belowbond feet and/or near low loss regions, such as e.g. current sensingpads or similar.

In another aspect, not only the temperature distribution but also thesoftness of the device 1 may be influenced: For example, the p-shorts171-2 may inject holes during commutation and thus provide sufficientsoftness.

With regard to the edge termination region 173 it should be noted thatin each of the embodiments of FIGS. 2-11 the backside region 17 furthercomprises a third backside zone 173, which is arranged inside the edgetermination region 16 The third backside zone 173 comprises a pluralityof regions of the first conductivity type 1731 and a plurality ofregions of the second conductivity type 1732 being arranged inalternating order in contact with the second load terminal structure 12,wherein the regions of the first conductivity type 1731 and the regionsof the second conductivity type 1732 have a smallest lateral extensionx4, x5 of at most 50 μm, such as at most 30 μm, for example at most 10μm.

The third backside zone 173 may be configured such that no significantinjection of electrons or holes occurs in this region during operationof the power semiconductor device 1. In this sense, the third backsidezone 173 may also be referred to as a “dead area.” As a result, nosubstantial amount of plasma will be present in the third backside zone173 and in the portions of the semiconductor body 10 that are locatedabove the third backside zone 173. In this way, a “high dynamicrobustness (HDR)” concept may be realized by means of the third backsideemitter zone(s) 173.

For example, a lateral extension x6 of the third backside zone 173 mayamount to at least 0.5 times, such as at least twice, or even at least 4times a vertical thickness z1 of the drift region 100 (see FIGS. 1A-B).

In the exemplary embodiments shown in FIGS. 2-11 the third backside zone173 is arranged in the edge termination region 16. In some embodiments,in which the power semiconductor device 1 has a gate (e.g. in case of aMOSFET or an RC-IGBT), such a third backside zone 173 may additionallyor alternatively be arranged (at least partially) below a gate runnerelectrode that is arranged at the front side 10-1.

In the exemplary embodiment shown in FIG. 3, both the first backsideemitter zone 171 and the second backside emitter zone 172 each comprisea plurality of second sectors 171-2, 172-2. In this case, the essentialdifference between the first backside emitter zone 171 and the secondbackside emitter zone 172 is in the a smallest lateral extension x2, x2′of the respective second sectors 171-2, 172-2 and in a lateral distanced2, d2′ between neighboring second sectors 171-2, 172-2: The secondregions 1722 of the second conductivity type in the second backsideemitter zone 172 have a larger lateral extension x2′ as compared to thelateral extension x2 of the second regions 1712 of the secondconductivity type in the first backside emitter zone 171. Also thelateral distance d2′ between neighboring second regions 1722 in thesecond backside emitter zone 172 is larger as compared to the lateraldistance d2 between neighboring second regions 1712 in the firstbackside emitter zone 171.

For example, an area ratio of the second regions of the secondconductivity type 1722 in the second backside emitter zone 172 vs. theregions of the first conductivity type 1740 in the second backsideemitter zone 172 may be similar or equal to an area ration of the secondregions of the second conductivity type 1712 in the first backsideemitter zone 171 vs. regions of the first conductivity type 1740 in thefirst backside emitter zone 172. Nevertheless, different emitter and/orinjection efficiencies may be realized in the first backside emitterregion 171 and the second backside emitter region 172 by means of asuitable design of the respective second regions 1712, 1722.

For example, the relatively coarse structure of the second sectors 172-2(relatively wide p-shorts) in the second backside emitter zone 172 mayyield a more efficient cathode in the second backside emitter zone 172as compared to the first backside emitter zone 171. As a result, duringoperation, similar to what has been described above with reference toFIG. 2, the plasma density as well as the static and dynamic losses maybe higher in the area of the second backside emitter zone 172 than inthe area of the first backside emitter zone 171.

In this context, it should be noted that a higher plasma density mayreduce the forward voltage of the diode 1. Further, in a parallelconnection of areas having different plasma densities and thus different(local) forward voltages, the current preferably chooses a path throughthe area having a relatively low forward voltage, i.e., the secondbackside emitter zone 172 in the present example. As a result, higherstatic and dynamic losses (yielding a local increase in temperature) mayoccur in the second backside emitter zone 172 as compared to the firstbackside emitter zone 171.

Further, with reference to all embodiments described above and in thefollowing, is should be noted with regard to softness that due to thedifferent design of the backside emitter regions 171, 172 (which mayhave an influence on, e.g., an initial plasma level, but also a reverserecovery behavior), the different backside emitter regions 171, 172 mayhave their maximum dl/dt (which is responsible for the overvoltage) atdifferent times. This may allow the overvoltage to be significantlyreduced.

Another softness-related aspect, which may be particularly relevant forthe illustrated variants having “dead areas” 171-1 as mentioned furtherbelow is the following: Here the plasma is strongly lowered at thebackside 10-2 without, however, providing softness-donating holes duringcommutation. The possibly early and strong decrease of the plasma offree charge carriers in the backside emitter regions 171, 172 havingsuch dead areas 171-1 can then be dampened by the respective otherbackside emitter region 171, 172, which at this point may still haveplasma and carry current and may thus be able to dampen theoscillations. For example, the design may be such that the “unsoftregion” 171, 172 is cleared from plasma before the “soft region” 171,172 is cleared from plasma.

FIG. 4 shows another variant embodiment, wherein the lateral distanced2′ between neighboring second regions 1722 in the second backsideemitter zone 172 is larger as compared to the lateral distance d2between neighboring second regions 1712 in the first backside emitterzone 171. In this embodiment, the smallest lateral extensions x2, x2′ ofthe second sectors 171-2, 172-2 in the first backside emitter zone 171and in the second backside emitter zone 172 are substantially equal.

In the exemplary embodiment shown in FIG. 5, the first backside emitterzone 171 comprises a plurality of first sectors 171-1, wherein each ofsaid first sectors 171-1 comprises a plurality of first regions 1711,the first regions 1711 being arranged at a lateral distance d11 fromeach other of at most three times the smallest lateral extension x1 ofthe first regions 1711. In other words, each of the first sectors 171-1comprises a plurality of first regions 1711 of the second conductivitytype being arranged in an alternating order with a plurality of regions1740 of the first conductivity type, similar to the third backside zone173 in the edge termination region 16 described above.

By contrast, similar to the embodiment of FIG. 2, the second backsideemitter zone 172 does not comprises any first or second sectors 172-1,172-2. Instead, in the embodiment of FIG. 5, the second backside emitterzone 172 consists of a region of the first conductivity type 1740forming a contiguous contact with the second load terminal structure 12and having a lateral extension d3 of at least ten times the smallestlateral extension x1 of the first regions 1711.

For example, while the emitter efficiency may be equal or similar in thefirst backside emitter region 171 and the second backside emitter region172 the presence of the relatively finely structured first sectors 171-1may reduce the injection efficiency of the first backside emitter region171 as compared to the second backside emitter region 172 so that no oronly a low injection of free charge carriers occurs by the finelystructured sectors. As a result, dynamic losses may be reduced in thearea of the first backside emitter region 171 as compared to the area ofthe second backside emitter region 172.

For example, the finely structured first sectors 171-1 may be configuredso as to support no significant injection of electrons or holes at all.In this case, the first sectors 171-1 may also be referred to as a “deadareas”, similar to what has been described above with regard to thethird zone 173 in the edge termination region 16.

In the exemplary embodiment shown in FIG. 6, the first backside emitterzone 171 comprises a plurality of first sectors 171-1, wherein each ofsaid first sectors 171-1 comprises a plurality of first regions 1711,the first regions 1711 being arranged at a lateral distance d11 fromeach other of at most three times the smallest lateral extension x1 ofthe first regions 1711. The second backside emitter zone 172 comprises aplurality of second sectors 172-2 each consisting of a second region1722 having a smallest lateral extension x2′ of at least ten times thesmallest lateral extension x1 of the first regions 1711.

In other words, in the embodiment of FIG. 6, the first backside emitterzone 171 is configured as in the embodiment of FIG. 5, whereas thesecond backside emitter zone 172 is configures as in the embodiments ofFIGS. 3 and 4.

For example, the relatively coarse structuring of the second regions1722 of the second conductivity type in the second backside emitter zone172 may reduce the cathode efficiency as compared to the configurationof the second backside emitter zone 172 according to FIG. 5. At the sametime, the relatively large lateral extension x2′ of the second regions1722 (wide p-short regions) may yield a strong injection of holes duringcommutation, thus improving the softness of the power semiconductordevice 1.

In the first backside emitter zone 171, the relatively finely structuredfirst sectors 171-1 may yield a similar cathode efficiency as the secondregions 1722 in the second backside emitter zone 172. However, theinjection efficiency may be relatively low due to the finely structuredfirst sectors 171-1. Since no additional holes are injected, lessswitching losses (and hence a less significant temperature increase) mayoccur in this region.

In the exemplary embodiment shown in FIG. 7, the first backside emitterzone 171 is configured as in the embodiments of FIGS. 5 and 6 describedabove. However, in the embodiment of FIG. 7, also the second backsideemitter zone 172 comprises a plurality of finely structured firstsectors 172-1, wherein the first sectors 172-1 have a larger lateralextension x11′ as compared to the lateral extension x11 of the firstsectors 171-1 in the first backside emitter zone 171. Further, a lateraldistance d1′ between neighboring first sectors 172-1 in the secondbackside emitter zone 172 is larger than a lateral distance d1 betweenneighboring first sectors 171-1 in the first emitter zone 171.

In the exemplary embodiment shown in FIG. 8, the first backside emitterzone 171 comprises a plurality of second sectors 171-2 (p-shorts) asdescribed above with reference to the first backside emitter zones 171of the embodiments of FIGS. 2 and 3. The second backside emitter zone172 exhibits a plurality of first sectors 172-1, each comprising asingle, relatively small first region 1721 of the second conductivitytype (“tiny p-shorts”). The first sectors 172-1 in the second backsideemitter zone 12 are spaced apart from one another by a relatively largelateral distance d1′, which exceeds the lateral distance d2 betweenneighboring second sectors 171-2 in the first backside emitter zone 171.

In the embodiment illustrated in FIG. 9, the second backside emitterzone 172 is configured as in the embodiment of FIG. 8. The firstbackside emitter zone 171 does not comprise any first or second sectors171-1, 171-2, but consists of a contiguous region 1740 of the firstconductivity type (e.g., an n⁺⁺-type region).

In the exemplary embodiment shown in FIG. 10, both the second backsideemitter zone 172 and the first backside emitter zone 171 exhibit aplurality of first sectors 171-1, 172-1 similar to the ones in thesecond backside emitter zone 172 in the embodiments of FIGS. 8 and 9(“tiny p-shorts”). In this case, the lateral distance d1 betweenneighboring first regions 1711 in the first backside emitter zone 171 isrelatively large and exceeds the lateral distance d1′ betweenneighboring first regions 1721 in the second backside emitter zone 172.

In the exemplary embodiment shown in FIG. 11, each of the first backsideemitter zone 171 and the second backside emitter zone 172 comprises aplurality of second sectors 171-2, 172-2 (“wide p-shorts”).Additionally, in the second backside emitter zone 172, a small firstregion 1721 (“tiny p-short”) is arranged in the vicinity of each secondregion 1722. In other variant embodiments (not illustrated), a pluralityof such tiny p-shorts 1721 may be arranged in the vicinity of some orall of the second regions 1722.

The exemplary embodiment shown in FIG. 12 is similar to the one of FIG.3 in that both the first backside emitter zone 171 and the secondbackside emitter zone 172 each comprise a plurality of second sectors171-2, 172-2, wherein a smallest lateral extension x2 of the secondregions 1712 of the second conductivity type in the first backsideemitter zone 171 is smaller than a smallest lateral extension x2′ of thesecond regions 1722 of the second conductivity type in the secondbackside emitter zone 172. In this case, however, a pitch P betweenneighboring second sectors 171-2, 172-2 is essentially equal in thefirst backside emitter region 171 and the second backside emitter region172, as illustrated.

For example, a p-area coverage ratio (i.e. the fraction of a total areaof the first or second backside emitter zone 171, 172 that is coveredwith second regions 1712, 1722) may be different in the first backsideemitter zone 171 as compared to a p-area coverage ratio in the secondbackside emitter zone 172, wherein the difference may amount to at least2%, such as at least 5%, at least 10%, at least 20%, or even at least40%.

Each of FIGS. 13A-E schematically and exemplarily illustrates a sectionof a horizontal cross-section of a power semiconductor device 1 inaccordance with one or more embodiments. In each case the cross-sectioncuts horizontally through the backside region 17 and illustratesexemplary geometric patterns in which the second regions 1712 of thesecond conductivity type may be arranged within the region 1740 of thefirst conductivity type. In FIGS. 12A-E, the second regions 1712 insidea first backside emitter zone 171, such as a first backside emitter zone171 of one of the embodiments described above, are shown as an example.It should be noted, however, that the same or similar geometricarrangements may also be chosen for the second regions 1722 inside oneor more second backside emitter zones 172, such as a second backsideemitter zone 172 of one of the embodiments described above.

As illustrated, in a horizontal cross-section, the second regions 1712may, for example, have at least one of: a circular configuration (FIGS.13A-B); a ring configuration (FIG. 13C); a stripe configuration (FIG.13D); and a honeycomb configuration (FIG. 13E).

FIGS. 14A-F each schematically and exemplarily show a section of ahorizontal cross-section through the backside region 17 in accordancewith one or more embodiments. For example, in FIG. 14A, a small sectionof a first backside emitter zone 171 is shown, wherein the secondregions 1712 of the second conductivity type, which are embedded in aregion 1740 of the first conductivity type, have a circularconfiguration, as illustrated in FIG. 13B.

FIG. 14B differs from FIG. 14A in that a very finely structured firstsector 171-1 of the kind that has been described above with referenceto, e.g., the first sectors 171-1, 172-1 in FIGS. 5-6 is additionallyprovided in a central position between the second regions 1712. Like thesecond regions 1712, also the first sector 171-1 has a circular shape.

FIG. 14C shows a configuration similar to the one of FIG. 14B, the onlydifference being that the circular first sector 171-1 has a largerdiameter and thus covers a larger area portion than in the embodiment ofFIG. 14B.

For example, the finely structured first sectors 171-1 may be configuredso as to support no significant injection of electrons or holes at all.In this case, the first sectors 171-1 may also be referred to as a “deadareas”, similar to what has been described above with regard to thefirst sectors 171-1 in the embodiments of FIGS. 5-6 as well as the thirdzone 173 in the edge termination region 16.

In FIGS. 14D-F, some further exemplary configurations of second regions1712 and first sectors 171-1 are shown, wherein the exemplaryembodiments of FIGS. 14D-E are based on a stripe configuration as shownin FIG. 13D. The exemplary embodiment of FIG. 14F is based on aconfiguration as shown in FIG. 13C, wherein in the variant according toFIG. 14F a square-shaped second region 1712 is surrounded by a finelystructured first sector 171-1.

It should be noted that while FIGS. 14A-F exemplarily show sections ofthe first backside emitter zone 171, the same or similar geometricarrangements may also be chosen for in one or more second backsideemitter zones 172.

In the above, embodiments pertaining to power semiconductor devices wereexplained.

For example, these semiconductor devices may be based on silicon (Si).Accordingly, a monocrystalline semiconductor region or layer, e.g., thesemiconductor body 10 and its regions/zones, e.g., regions etc. can be amonocrystalline Si-region or Si-layer. In other embodiments,polycrystalline or amorphous silicon may be employed.

It should, however, be understood that the semiconductor body 10 and itsregions/zones can be made of any semiconductor material suitable formanufacturing a semiconductor device. Examples of such materialsinclude, without being limited thereto, elementary semiconductormaterials such as silicon (Si) or germanium (Ge), group IV compoundsemiconductor materials such as silicon carbide (SiC) or silicongermanium (SiGe), binary, ternary or quaternary III-V semiconductormaterials such as gallium nitride (GaN), gallium arsenide (GaAs),gallium phosphide (GaP), indium phosphide (InP), indium galliumphosphide (InGaPa), aluminum gallium nitride (AlGaN), aluminum indiumnitride (AlInN), indium gallium nitride (InGaN), aluminum gallium indiumnitride (AlGaInN) or indium gallium arsenide phosphide (InGaAsP), andbinary or ternary II-VI semiconductor materials such as cadmiumtelluride (CdTe) and mercury cadmium telluride (HgCdTe) to name few. Theaforementioned semiconductor materials are also referred to as“homojunction semiconductor materials”. When combining two differentsemiconductor materials a heterojunction semiconductor material isformed. Examples of heterojunction semiconductor materials include,without being limited thereto, aluminum gallium nitride (AlGaN)-aluminumgallium indium nitride (AlGaInN), indium gallium nitride(InGaN)-aluminum gallium indium nitride (AlGaInN), indium galliumnitride (InGaN)-gallium nitride (GaN), aluminum gallium nitride(AlGaN)-gallium nitride (GaN), indium gallium nitride (InGaN)-aluminumgallium nitride (AlGaN), silicon-silicon carbide (SixC1-x) andsilicon-SiGe heterojunction semiconductor materials. For powersemiconductor switches applications currently mainly Si, SiC, GaAs andGaN materials are used.

Spatially relative terms such as “under”, “below”, “lower”, “over”,“upper” and the like, are used for ease of description to explain thepositioning of one element relative to a second element. These terms areintended to encompass different orientations of the respective device inaddition to different orientations than those depicted in the figures.Further, terms such as “first”, “second”, and the like, are also used todescribe various elements, regions, sections, etc. and are also notintended to be limiting. Like terms refer to like elements throughoutthe description.

As used herein, the terms “having”, “containing”, “including”,“comprising”, “exhibiting” and the like are open ended terms thatindicate the presence of stated elements or features, but do notpreclude additional elements or features.

With the above range of variations and applications in mind, it shouldbe understood that the present invention is not limited by the foregoingdescription, nor is it limited by the accompanying drawings. Instead,the present invention is limited only by the following claims and theirlegal equivalents.

What is claimed is:
 1. A power semiconductor device, comprising: asemiconductor body having a front side and a backside; a first loadterminal structure coupled to the front side and a second load terminalstructure coupled to the backside; an active area of the semiconductorbody configured to conduct a load current between the first loadterminal structure and the second load terminal structure; a driftregion of the semiconductor body having a first conductivity type andconfigured to conduct the load current; a backside region of thesemiconductor body arranged at the backside and comprising, inside theactive area, a first backside emitter zone and a second backside emitterzone, wherein at least one of the first backside emitter zone and thesecond backside emitter zone comprises: a plurality of first sectorseach comprising at least one first region of a second conductivity typearranged in contact with the second load terminal structure and having asmallest lateral extension of at most 50 μm; and/or a plurality ofsecond sectors each consisting of a second region of the secondconductivity type arranged in contact with the second load terminalstructure and having a smallest lateral extension of at least 50 μm;wherein the second backside emitter zone differs from the first backsideemitter zone at least in one of the following: the presence of the firstsectors; the presence of the second sectors; the smallest lateralextension of the first sectors; the smallest lateral extension of thesecond sectors; a lateral distance between neighboring first sectors; alateral distance between neighboring second sectors; a smallest lateralextension of the first regions; and a lateral distance betweenneighboring first regions within the same first sector.
 2. The powersemiconductor device of claim 1, wherein an area extension of each ofthe first backside emitter zone and the second backside emitter zoneamounts to at least 5% of the active area.
 3. The power semiconductordevice of claim 1, wherein a lateral distance between neighboring firstand/or second sectors amounts to at least 50 μm.
 4. The powersemiconductor device of claim 1, wherein the first backside emitter zoneand/or the second backside emitter zone comprises a plurality of firstsectors, wherein each of the first sectors comprises a plurality offirst regions, the first regions being arranged at a lateral distancefrom each other of at most three times the smallest lateral extension ofthe first regions.
 5. The power semiconductor device of claim 1,wherein: the first backside emitter zone comprises a plurality of firstsectors, each of the first sectors comprising a plurality of firstregions, the first regions being arranged at a lateral distance fromeach other of at most three times the smallest lateral extension of thefirst regions; and the second backside emitter zone comprises a regionof the first conductivity type forming a contiguous contact with thesecond load terminal structure and having a lateral extension of atleast ten times the smallest lateral extension of the first regions. 6.The power semiconductor device of claim 1, wherein: the first backsideemitter zone comprises a plurality of first sectors, each of the firstsectors comprising a plurality of first regions, the first regions beingarranged at a lateral distance from each other of at most three timesthe smallest lateral extension of the first regions; and the secondbackside emitter zone comprises a plurality of second sectors eachcomprising a second region having a smallest lateral extension of atleast ten times the smallest lateral extension of the first regions. 7.The power semiconductor device of claim 1, wherein the backside regionfurther comprises a third backside zone which comprises a plurality ofregions of the first conductivity type and a plurality of regions of thesecond conductivity type arranged in alternating order in contact withthe second load terminal structure, the regions of the firstconductivity type and the regions of the second conductivity type havinga smallest lateral extension of at most 50 μm.
 8. The powersemiconductor device of claim 7, wherein the third backside zone isarranged in an edge termination region of the semiconductor body.
 9. Thepower semiconductor device of claim 7, wherein the third backside zoneis arranged below a gate runner electrode that is arranged at the frontside.
 10. The power semiconductor device of claim 7, wherein a lateralextension of the third backside zone amounts to at least 0.5 times avertical thickness of the drift region.
 11. A power semiconductordevice, comprising: a semiconductor body having a front side and abackside; a first load terminal structure coupled to the front side anda second load terminal structure coupled to the backside; an active areaof the semiconductor body configured to conduct a load current betweenthe first load terminal structure and the second load terminalstructure; a drift region of the semiconductor body having a firstconductivity type and configured to conduct the load current; a backsideregion of the semiconductor body arranged at the backside andcomprising, inside the active area, a first backside emitter zone and asecond backside emitter zone, wherein at least one of the first backsideemitter zone and the second backside emitter zone comprises: a pluralityof second sectors each comprising a second region of the secondconductivity type, the second regions being arranged in contact with thesecond load terminal structure and having a smallest lateral extensionof at least 50 μm; wherein the first backside emitter zone has each of afirst emitter efficiency and a first injection efficiency; wherein thesecond backside emitter zone has each of a second emitter efficiency anda second injection efficiency at the nominal current; wherein: the firstemitter efficiency differs from the second emitter efficiency by atleast 1%; and/or the first injection efficiency differs from the secondinjection efficiency by at least 5%; and/or an injected hole charge ofthe first backside emitter zone differs from an injected hole charge ofthe second backside emitter zone by at least 10%; and/or an averagebackside plasma concentration associated with the first backside emitterzone differs from an average backside plasma concentration associatedwith the second backside emitter zone by at least 5%.
 12. A powersemiconductor device, comprising: a semiconductor body having a frontside and a backside; a first load terminal structure coupled to thefront side and a second load terminal structure coupled to the backside;an active area of the semiconductor body configured to conduct a loadcurrent between the first load terminal structure and the second loadterminal structure; a drift region of the semiconductor body having afirst conductivity type and configured to conduct the load current; abackside region of the semiconductor body arranged at the backside andcomprising, inside the active area, a first backside emitter zone and asecond backside emitter zone, wherein each of the first backside emitterzone and the second backside emitter zone comprises a plurality ofregions of a second conductivity type arranged in contact with thesecond load terminal structure and a plurality of regions of the firstconductivity type arranged in contact with the second load terminalstructure; wherein a dopant concentration in a respective centralportion of the regions of the second conductivity type in the firstbackside emitter zone is essentially equal to a dopant concentration ina respective central portion of the regions of the second conductivitytype in the second backside emitter zone; wherein a dopant concentrationin a respective central portion of the regions of the first conductivitytype in the first backside emitter zone is essentially equal to a dopantconcentration in a respective central portion of the regions of thefirst conductivity type in the second backside emitter zone; wherein thefirst backside emitter zone has each of a first emitter efficiency and afirst injection efficiency; wherein the second backside emitter zone haseach of a second emitter efficiency and a second injection efficiency atthe nominal current; wherein: the first emitter efficiency differs fromthe second emitter efficiency by at least 1%; and/or the first injectionefficiency differs from the second injection efficiency by at least 5%;and/or an injected hole charge of the first backside emitter zonediffers from an injected hole charge of the second backside emitter zoneby at least 10%; and/or an average backside plasma concentrationassociated with the first backside emitter zone differs from an averagebackside plasma concentration associated with the second backsideemitter zone by at least 5%.
 13. The power semiconductor device of claim12, wherein in a horizontal cross-section through the first backsideemitter zone and/or the second backside emitter zone, regions of thesecond conductivity type have at least one of: a circular configuration;a ring configuration; a stripe configuration; and a honeycombconfiguration.
 14. The power semiconductor device of claim 12, whereinthe semiconductor body comprises a field stop region arranged betweenthe drift region and the backside region and having a higher dopantconcentration of the first conductivity type than the drift region. 15.The power semiconductor device of claim 14, wherein the field stopregion has come into being by means of proton implantation.
 16. Thepower semiconductor device of claim 15, wherein an end of range of ashallowest dopant concentration peak is located in at a depth a rangefrom 1 μm to 4 μm below a backside surface of the semiconductor body.17. The power semiconductor device of claim 14, wherein the backsideregion comprises one or more regions of the first conductivity typearranged in contact with the second load terminal structure and having ahigher dopant concentration of the first conductivity type than thefield stop region.
 18. The power semiconductor device of claim 14,wherein a dopant concentration of the second conductivity type of thefirst regions and/or a dopant concentration of the second regions islarger than the dopant concentration of the first conductivity type ofthe field stop region.
 19. The power semiconductor device of claim 12,wherein the power semiconductor device is or comprises at least one of:a power diode; an RC-IGBT; a power MOSFET.